How to Save Tender Summer Bulbs for Next Season

By: Jennifer Howell

Do you grow summer flowering bulbs like canna, dahlias and glads? Find everything you need to know about how to save these tender summer bulbs, corms, and tubers to grow again next year.

Don’t toss your tender summer bulbs!

If you love growing tender summer bulbs, such as cannas (Canna spp. and hybrids) or dahlias (Dahlia hybrids), but they aren’t hardy in your zone, save tender bulbs over the winter and grow them again next year!

What is a “tender bulb”?

Technically, not all the plants called “tender bulbs” are actually bulbs. There are also corms, rhizomes and tubers. They’re all enlarged root-like structures that store energy to resurrect these plants each spring. But to keep things simple, they’re often all referred to as tender bulbs. For most tender bulbs, you’ll follow the same process of digging, curing and storing. Learn more about each step below, and then scroll down for specific information on some of the most popular corms, rhizomes, tubers and bulbs.

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ht-save-tenderbulbs-dig-dahlia: Here we see dahlia tubers being dug up to be saved over the winter.

Step 1: Dig up the tender summer bulb

Digging when the soil is moist, not muddy or dried and cracked, makes it easier to lift and clean the tender bulbs. If you dig too early in the season, your bulb may not have stored enough energy to grow a healthy plant next year. Too late and the ground may have frozen hard and the tender bulb with it.

Most plants can be lifted when their foliage yellows and dies back, or after the first hard freeze, when leaves turn crispy and dried or black and mushy.

Tools to Help You Dig Bulbs:
Garden Fork
Mini-Shovel
Garden Gloves

ht-save-tenderbulbs-dig-cure: A mesh screen works great to lay tender bulbs out to be cured or dried before being put away for storage over the winter.

Step 2: Trim, clean & cure the tender bulb

Trim the stems and clean soil off the tender bulb so fungi, soilborne diseases or insects won’t ruin it during storage. After you have your bulb cleaned, inspect for diseased tissue, shriveling from dehydration and insect damage from borers or bulb mites. Discard any that don’t look healthy and firm. Cure tender bulbs for a few days up to a few weeks in a well-ventilated area so they can dry completely. Excess moisture can cause bulbs to get moldy and rot over the winter.

Tubers can be sprayed with water to clean soil out of the crevices, as long as they are dried completely after so they won’t mold.
Don’t wash corms — they have a papery covering that shouldn’t get wet before storage. Instead, air dry or cure them out of direct sunlight in a well-ventilated spot at 60 to 70 degrees F. After two to three weeks, use a paintbrush to remove any soil still clinging.

ht-save-tenderbulbs-store: After being cleaned and cured, proper storage will ensure healthy bulbs for next spring.

Step 3: Store the tender bulb

Keeping tender summer bulbs cool and in darkness is important to maintain dormancy and ensure healthy bulbs for next year. On a shelf in a chilly basement or garage is a good place to store tender bulbs for the winter.

Tubers and rhizomes are fleshier, so they need a bit of humidity to prevent them from drying out over the winter. Store them in slightly moistened peat moss or vermiculite in a newspaper-lined crate, cardboard box or shoe box.
Corms and bulbs like it cool, dark and dry. Once they’ve had a curing period, pack them away in small paper sacks with their cultivar name written on the outside or a mesh produce bag with a label.

How to dig and store 7 common tender summer bulbs

Now scroll down for 7 common tender bulbs and tips to help prepare them for storage in cold winter zones!

Calla lily (Zantedeschia aethiopica)

Using a shears, cut yellowed foliage 1 to 2 in. from the rhizome after the first frost. After it has dried up, you can remove the stems completely.

Type Rhizome
When to dig After frost has killed the foliage, let it dry several days in the ground, then dig the rhizomes.
How to cure Brush off excess soil and remove dried stems at the rhizome after setting aside for two to three days.
How to store Store in slightly moist peat moss, vermiculite or sand at 40 to 50 degrees F.

Crocosmia (Crocosmia spp. and hybrids)

Small cormels will form off roots. Snip them apart and plant for more divisions. Old, dried corms, like you see in the photo above, can be discarded.

Type Corm
When to dig These plants are often hardy to 25 degrees so for zones where they won’t winter over dig six to eight weeks after blooms finish or after a killing freeze.
How to cure Brush off soil but do not wash. Cure corms two to three weeks at 60 to 70 degrees F in a well-ventilated area. Remove the old corm and discard — do not compost any throwaways as they are invasive in areas where they are hardy.
How to store Store in paper or mesh bags in a cool, dry area, such an unheated garage, at 35 to 40 degrees F.

Gladiolus (Gladiolus hybrids)

New corms form on the original gladiolus corm planted in the spring. Peel the old shriveled one off the bottom and discard it, saving the new one for next year. Check out our article on saving glad corms for a step-by-step how-to.

Type Corm
When to dig Dig corms six to eight weeks after bloom when foliage is yellowing or after a killing frost.
How to cure Cure corms for two to three weeks on a screen in a well-ventilated area at 60 to 70 degrees F. After curing, remove old dried-up corm and discard. Collect small cormels and plant in a 6-in. pot if you like.
How to store Store in paper or mesh bags in a dry, well-ventilated location at 35 to 40 degrees F.

Tuberose (Polianthes tuberos)

“Daughter bulbs” form at the base of the main rhizome. They’ll bloom after they reach the size of your thumb, so pull to separate the roots and plant them, leaving tinier ones still attached to grow another season.

Type Rhizome
When to dig Dig rhizomes after a killing frost.
How to cure Brush off excess soil and dry for two to three days.
How to store Store in perforated plastic bags with sand or vermiculite. If you don’t want divisions, tubers can also be stored in the pots they grew in; just quit watering in late fall and keep it dry over winter. Store at 55 to 65 degrees F.

Canna (Canna hybrids)

Use a paintbrush to clean soil off rhizomes before inspecting them for damge. Wash roots with water if brushing doesn't get it all off.

Type Rhizome
When to dig Let foliage dry a few days after a killing frost, then cut stems 3 in. from the rhizome and just above the soil line. Dig the clump.
How to cure Wash off all the soil. Let the rhizomes cure several days in a cool, well-ventilated spot. Make sure they are dry before storing.
How to store Place in moist sphagnum peat, vermiculite, or sand in covered boxes. You can also store them loosely in plastic bags, checking periodically to release condensation or mist with water if they are drying up. Rhizomes should be humid, not wet. Store at 40 to 50 degrees F.

Dahlia (Dahlia hybrids)

You can use a permanent marker to write the cultivar name directly on a fleshy tuber like this dahlia.

Type Tuber
When to dig One week after a blackening frost, when foliage turns dark and wilts, cut stems to 1 to 2 in. from the soil surface, then dig.
How to cure Wash clump of tubers to remove excess soil, then dry stemside down for two to three days so moisture drains out of the hollow stems and won’t mold.
How to store Store covered in slightly moist sphagnum peat vermiculite in boxes or plastic bags with perforations. Check every couple weeks and air out if condensation forms or mist with water if the tubers are withering and drying out. Keep at 40 to 50 degrees F.

Peruvian daffodil (Hymenocallis x festalis)

Dry vermiculite prevents mold while still helping the roots retain moisture. Be sure to cover them completely so they don’t dry out. Burying them upside down discourages early sprouting.

Type Bulb
When to dig Dig before frost when foliage is yellowing in late fall.
How to cure Separate clumps of bulbs carefully to prevent damaging large roots still attached to the bulb.
How to store Place upside down in dry vermiculite or sand to discourage sprouting midwinter. Store at 60 to 65 degrees; any colder and the bulbs may not bloom the next year.